Nosology is the branch of medical science that deals with the orderly classification of diseases.
While the practice of medicine has experienced major technological advances in recent years, nosologic systems (e.g. International Classification of Diseases-10 and the Diagnostic and Statistical Manual-IV of the American Psychiatric Association) present at times a confusing array of diagnostic possibilities. Many diseases/disorders may even be represented in more than one place in the diagnostic system. Lack of a comprehensive framework leads to diagnostic confusion in the clinical teaching and often in the research setting. Clearly organization and orderliness are needed to better discriminate between entities.
Classification issues have historic roots. Hippocrates suggested that “whoever undertakes to speak or write on medicine, should have first laid themselves some hypothesis as to their argument, such as hot or cold or moist or dry or whatever else they choose, thus reducing their subject within a narrow compass.” The work of Thomas Sydenham on acute diseases first published in 1675 is seminal. Sydenham suggested that all diseases can be classified as to a certain definite species in the same manner as botanists describe their plants. He further suggested that pathologic phenomena should be described in precise detail in the same way a portrait painter seeks to capture the likeness of a subject. He also noted that particular and constant symptoms should be distinguished from accidental phenomena. John Locke, in describing Sydenham, suggested that he had a poor opinion of those who attempted to look at disease from a chemical point of view. On the other hand, he noted that Sydenham recognized the utility of chemotherapeutics, recognizing, for instance, that certain chemicals could induce vomiting, implying that treatment outcome was not a good basis for classification but overlooking its potential value as validator of diagnosis.
Carl Linné graduated as a Doctor of Medicine in 1735. While he is best known for his biological classification system (e.g. phyla, genera, species), his attempt to use this approach for medicine was never widely accepted, principally because of a confusion between the definitions of symptom and disease. Laennec in 1826 was among the first to link symptoms to pathologic anatomy when he described the disseminated pathology of tuberculosis. In the mid-Nineteenth Century, the pathophysiologic basis of disease came into focus. Methods for counting cells, methods for the measurement of the color of blood as well as methods for the examination of urine were developed. In the late 19th century, an etiologic approach for the classification of disease became possible with the identification of a specific bacteria as the cause for a specific disease (Koch-Pasteur). This became the best first good example of using the best and most robust discriminator, etiology. There was, therefore, an evolutionary progression from phenomenologic descriptions to those which were base on etiology. Each reflected at the time the state of knowledge.
Many disorders in psychiatry and neurology still can only be described phenomenologically. While seemingly the least robust, pheomenologic validity is attainable. Skinner suggested that a phenomenologically based system should have certain features so as to make descriptions of specific entities valid. These include reliability; that is, agreement across examiners using the same diagnostic methodology; coverage, referring to the applicability of the classification domain of the patients for which it was intended; descriptive validity implying homogeneity in characterizing behavioral symptoms, personality characteristics, social history data, and other kinds of information which are used to make a diagnosis and lastly; predictive validity where a classification system can determine the potential effectiveness of treatment or the natural history of a psychiatric disorder. While Skinner's conceptual framework was meant to be applied to psychiatric disorders described phenomenologically, it can obviously be generalized. It can also provide a mechanism for a classification system.
Classification in science is important to medicine. A successful and, therefore, useful classification should be simple and easy to use. It should be organized hierarchically and have the flexibility to reflect the state of the art as it evolves. The disease/disorder should be defined etiologically through the rigorous application of the scientific method.
Texts and text book series have proposed an orderly classification of features used in diagnosis.
Accordingly, it is an object of the present invention to provide a computer based classification system which can be used by physicians in the diagnosis of patients.